Project Summary/ Abstract The proposed K01 Mentored Research Scientist Development Award will provide the applicant with advanced training and skills to launch an independent research program focused on developing and evaluating implementation interventions that reduce mental health (MH) disparities for ethnically diverse families. This K01 proposal seeks to develop an evidence base for leveraging Lay Health Workers (LHW), community members without formalized MH training, to address determinants of MH disparities related to client demand for and the supply of behavioral parent training (BPT) programs in underserved communities. The community- partnered development and pilot evaluation of the LHW Enhancing Engagement for Parents (LEEP) implementation intervention will train LHW to conduct outreach and promote treatment engagement and skill acquisition for Latino families in Parent-Child Interaction Therapy (PCIT). Aim 1 of the study will assess the current context of LHW mobilization in children's evidence-based service delivery in community MH agencies through qualitative interviews with agency leaders and LHW, and quantitative surveys of LHW. Mixed-method analyses of these data will inform the development of LEEP. In Aim 2, the applicant will partner with community stakeholders to develop an implementation plan, structure, and process materials (e.g., fidelity measures) for LEEP. Aim 3 will pilot LEEP within an effectiveness/implementation hybrid design. Qualitative and quantitative data will inform the evaluation of LEEP including its feasibility, acceptability, and effects on client engagement, clinical outcomes, and implementation outcomes. The proposed study is well suited to the community setting and expertise the applicant brings to the project. Los Angeles County Department of MH (LACDMH) has invested considerable efforts in the implementation of evidence-based practices, including PCIT. The applicant's postdoctoral fellowship focused a MH policy reform within LACDMH, providing her insight into this large system of care. To meet her career objectives and the aims of this research project, the applicant requires additional training in: (1) implementation and health services research methodology to measure and reduce MH disparities; (2) application of implementation strategies and theories to inform the development of interventions to address supply and demand determinants of disparities; (3) approaches to improve parental entry into and engagement in treatment. Mentorship and consultation from primary sponsor, Dr. Jeanne Miranda (MH disparity reduction), co-sponsor, Dr. Anna Lau (MH disparities, implementation science), Dr. John Landsverk (implementation science), Dr. Lisa Saldana (economic evaluations of implementation efforts), Dr. Maryam Kia-Keating (community-partnered research, LHW models), Dr. Camille Nebeker (LHW training, responsible conduct of research), Dr. Emily Winslow (parent engagement), Dr. Karen Nylund-Gibson (multilevel statistical models) and Dr. Susan Ettner (health economics) will facilitate this training.